Effect Of Irrigation Amount And Film Mulching On Carbon Sequestration In Wheat-maize Rotation System

Irrigation and film mulching are widely used in northwest of China to improve water use efficiency and crop yield,but Irrigation and film mulching can influence greenhouse gas(GHG)emission and carbon footprint in agricultural production.In this study,annual GHG emissions(including CO2,CH4,and N2O)were monitored with static opaque chamber and gas chromatography from a wheat-maize rotation system with different irrigation treatments in the Guanzhong Plain of China during 2014-2015.Net global warming potential(NGWP)and carbon footprint were used to evaluate the influences of different irrigation amounts on GHG emissions and composition of carbon footprint of crop production.The results showed that soils were generally sinks of GHGs under different irrigation treatments.Irrigation amounts experiment were a total of four different irrigation treatments,e.g.W0,W120,W180,and W240,where subscripts represent the irrigation amounts in mm.Four mulching treatments were no mulching(CK),semi-film mulching(BM),ridge-furrow planting with film mulching over ridge(LM),and whole film mulching(QM).The results show that:1)Irrigation amounts experiment: Compared with treatment W0,wheat yields of treatments W120,W180,and W240 increased by 31.3%,44.3%,and 33.7%,while corn yields increased by 9.9%,22.6%,and 33.8%,respectively.Similarly,annual CO2 emission increased by 22.2%,24.3% and 15.1% and annual N2 O emission by 18.6%,67.8%,and 91.5%,respectively,while annual CH4 absorption decreased by 51.7%,79.6%,and 97.8%,respectively.The values of NGWP increased by 20.1%,31.6%,and 31.4%,respectively.The carbon footprint of treatment W120 was 19.1% lower than W0,while W180 and W240 showed no significant difference.Treatments W120 and W240 increased carbon footprint per unit crop yield by 44.5% and 23.3%,respectively,while W180 showed no significant difference.Both considering the economic and environmental effects of different irrigation amounts,we recommend the irrigating amount of 180 mm for the wheat-maize rotation system in the Guanzhong Plain of China for the purposes of water saving and carbon sequestration.2)Film mulching experiment: Compared with CK,the BM,LM and QM increased annual crop yield by 9.0%,16.5%,and 26.6%.Similarly,the BM,LM and QM increased annual CO2 emission by 33.9%,9.3% and 31.6% and annual N2 O emission by 22.9%,14.3%,and 47.1%,respectively.However,annual CH4 emissions showed no significant difference compared with CK.In additions,NGWP increased by 9.0%,16.7% and 26%,respectively.The carbon footprint of LM and QM were 33.2% and 21.9% lower than that of CK,while BM showed no significant difference compared with CK.Compared with carbon footprint per unit crop yield of treatment CK,BM increased by 16.3%,while LM decreased by 13.1%.Meanwhile,QM showed no significant difference.Considering both the economic and environmental effects of different mulching treatments,we recommended ridge-furrow planting with film mulching over ridge in the wheat-maize rotation system for carbon sequestration and greenhouse gas reduction in Guanzhong Plain of China for the purposes of water saving and carbon sequestration.